ExtJs 5: TreePanel: Not getting the default leaf icons and lines

I created a sample TreePanel using Sencha ExtJs 5. I followed the sample example in the documentations and I am able to see the items (leaves and branches) but they are not coming as a Tree, but as a list.

Here is my code:

Store:

Ext.define('MyApp.store.ResourcesStore', {
extend : 'Ext.data.TreeStore',
root : {
    expanded : true,
    children : [ {
        text : "UI Forms",
        leaf: false,
        expanded : true,
        children : [ {
            text : "Web",
            leaf : true
        }, {
            text : "Smart Phone",
            leaf : true
        }, {
            text : "Tablet",
            leaf : true
        }, ]
    }, {
        text : "Reports",
        leaf : true
    }, {
        text : "Dashboards",
        leaf : true
    }, {
        text : "Entities",
        leaf : true
    }, {
        text : "Queries",
        leaf : true
    }, {
        text : "Services",
        leaf : true
    } ]
}
});

View:

Ext.define('MyApp.view.leftpanel.ResourcesView', {
extend : 'Ext.TreePanel',
xtype : 'resources-panel',
title : 'Resources',
store : 'ResourcesStore',
rootVisible : false
});

Here is what my output looks like:

After executing the sencha app build command: Accordion panel got impacted.

If you use Sencha Cmd then you most likely need to:

sencha app refresh
sencha ant sass

and if it does not help then

sencha app build

Application bootstrap needs to know that you are using trees so it knows which css to load.